In chloralose anaesthetised cats the receptive field organisation and response properties of neurones of the spinal trigeminal nucleus were exmained and compared with the discharge characteristics of afferent units from vibrissae. 2. The response properties of the primary afferent discharges were preserved in at least a proportion of the second order cells, 82% of those which responded to movements of the maxillary vibrissae had phasic discharges and 18% had tonic discharges. 3. The discharge characteristics of the two main types of primary afferent slowly-adapting units (St I and St II) were distinguishable in the tonically active cells of the nucleus. These two groups showed (i) substantially different interspike interval distributions, (ii) different adaptive properties and (iii) different directional sesitivity. The two categories were designated nuclear type I and type II in accordance with the classification of primary afferent slowly-adapting units. 4. A loss of stimulus information was deduced from a consistent increase in the variability of the second order discharges compared with their presumed afferent input, but this information loss may be important in allowing the linear summation of discharges at the level of the thalamus.
摘要
在水合氯醛麻醉的猫中，研究了三叉神经脊束核神经元的感受野组织和反应特性，并与触须传入单位的放电特征进行了比较。2. 至少一部分二级细胞保留了初级传入放电的反应特性，对上颌触须运动有反应的细胞中，82% 有相位放电，18% 有紧张性放电。3. 两种主要类型的初级传入慢适应单位（St I 和 St II）的放电特征在该核的紧张性活动细胞中是可区分的。这两组表现出（i）显著不同的峰间间隔分布，（ii）不同的适应特性，以及（iii）不同的方向敏感性。根据初级传入慢适应单位的分类，这两类被指定为核 I 型和 II 型。4. 与假定的传入输入相比，二级放电的变异性持续增加，由此推断存在刺激信息丢失，但这种信息丢失在允许丘脑水平的放电线性总和方面可能很重要。
